| Sperry 403 is former New Haven Railroad Mack railbus 18 built 1954 in an order of nine units (NH 11-19). They were quickly mothballed and two, 19 and 18 were sold to Sperry in 1958 and became SRS 402 and 403 respectively. 403 is a self-propelled inspection car equipped with Sperry ultrasonic track inspection equipment. With its compact loading gauge, 403 is often used by NYCT on the New York City Subway system due to the narrow tunnels and smaller loading gauge than the North American national network including Class I main lines and connecting short lines. |